1. Field of the Invention
The present invention relates to a vehicle electric power supply system comprising: an electric power generating source; a battery; a first voltage converter configured to raise a voltage of the electric power generating source; a second voltage converter configured to raise a voltage of the battery; and an electric power converter configured to supply voltages, which are obtained by conversions by the respective first and second voltage converters, to a vehicle load.
2. Description of the Related Art
Japanese Patent Application Laid-open No. 2006-345606 and Japanese Patent Application Laid-open No. 2008-193864 have made known hybrid vehicles in which: a power control unit is placed in an engine compartment; and a battery unit is placed under rear seats or in a trunk. In addition, Japanese Patent Application Laid-open No. 2007-39020 has made known a hybrid vehicle in which a power control unit and a battery are placed in or under the back of rear seats. Meanwhile, in fuel cell vehicles and electric vehicles, a power control unit is placed in a motor compartment in most cases because no engine is mounted thereon, while a battery is often placed under a vehicle interior or in a trunk. In some cases, the power control unit is placed in a space under the vehicle interior instead of in the motor compartment, depending on the configuration of the power control unit.
In the meantime, for the viewpoint of enhancing merchantability, it is desirable to widen the vehicle interior and also the luggage containing space in the vehicle's rear portion. However, there is a limit to the widening of the vehicle interior and the luggage containing space in the vehicle's rear portion, in the case of the configuration in which the battery unit is placed under the rear seats or in the trunk as disclosed in the above-described Japanese Patent Application Laid-open Nos. 2006-345606 and 2008-193864, and the configuration in which the power control unit and the battery are placed in or under the back of the rear seats as disclosed in the above-described Japanese Patent Application Laid-open No. 2007-39020. Furthermore, in a case where a vehicle has a configuration in which the power control unit and the battery are placed in their respective separate locations, a space in which to arrange electric wires and cooling pipes connecting the power control unit and the battery needs to be secured under the floor. The space in which to arrange the electric wires and the cooling pipes is likely to hinder a wider space from being secured for the vehicle interior. In addition, the electric wires and the cooling pipes need protection covers for the protection from protrusions and the like on the road surface. This entails increase in the weight of the vehicle. Moreover, from the viewpoint of securing the electricity safety, further safety measurements are needed for the protection covers of the electric wires and the cooling pipes. In the case where the power control unit and the battery are placed in their separated locations, consideration needs to be given to safety measurements such as the containing of the power control unit and the battery in their respective separated rigid cases. This entails increase in the weight of the vehicle as well.